GRB 140528A

S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, D. Svinkin, and 
T. Cline on behalf of the Konus-Wind team,

K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. 
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, 
on behalf of the Fermi GBM team, report:

The long-duration GRB 140528A has been observed by Fermi (GBM: trigger 
423000325), Konus-Wind, INTEGRAL (SPI-ACS), and MESSENGER (GRNS), so 
far, at about 72323 s UT (20:05:23).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
   ---------------------------------------------
    RA(2000), deg                 Dec(2000), deg
   ---------------------------------------------
   Center:
    280.731 (18h 42m 55s) -59.080 (-59d 04' 47")
   Corners:
    281.417 (18h 45m 40s) -58.757 (-58d 45' 25")
    281.160 (18h 44m 38s) -59.219 (-59d 13' 09")
    280.032 (18h 40m 08s) -59.394 (-59d 23' 38")
    280.306 (18h 41m 13s) -58.938 (-58d 56' 16")
   ---------------------------------------------
The error box area is 864 sq. arcmin, and its maximum dimension is 57 
arcmin (the minimum one is 24 arcmin).

The center of the GBM ground position (given in 
glg_tcat_all_bn140528837_v01.fit) is 1.29 deg from the center of the box.

This box may be improved.

A triangulation map is posted at 
http://www.ioffe.ru/LEA/GRBs/GRB140528_T72325/IPN/

Details of the Konus-Wind observation will be given in a forthcoming GCN 
Circular.

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, moderately intense GRB 140528A (Golenetskii et al., 
GCN 16339
Loading...
 
 ) triggered Konus-Wind at T0=72325.953 s UT (20:05:25.953).
The burst light curve shows a multi-peaked structure with a total 
duration of ~16 s. The emission is seen up to ~3 MeV.

As observed by Konus-Wind, the burst had a fluence of 
2.4(-0.3,+0.3)x10^-5 erg/cm2, and a 64-ms peak flux, measured from 
T0+10.112 s, of 5.1(-1.3,+1.3)x10^-6 erg/cm2/s (both in the 20 keV - 10 
MeV energy range).

The time-integrated spectrum of the burst (measured from T0 to T0+16.640 
s) is best fit in the 20 keV - 5 MeV range
by a GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.59(-0.14,+0.17),
the high energy photon index beta = -2.8(-0.7,+0.3),
the peak energy Ep = 202(-20,+21) keV,
chi2 = 47/72 dof.

The spectrum near the maximum count rate (measured from T0+8.448 s to 
T0+16.640 s) is best fit in the 20 keV - 5 MeV range
by a GRB (Band) model with the following parameters:
the low-energy photon index alpha =-0.40(-0.23,+0.27),
the high energy photon index beta = -2.7(-1.1,+0.3),
the peak energy Ep = 177(-22,+27) keV,
chi2 = 60/69 dof.

The Konus-Wind light curve of this GRB is available at 
http://www.ioffe.ru/LEA/GRBs/GRB140528_T72325/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

Matthew Stanbro (UAH) reports on behalf of the Fermi GBM Team:

"At 20:05:22.75 UT on 28 May 2014, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 140528A (trigger 423000325 / 140528837)
which was triangulated by IPN (Golenetskii et al. 2014, GCN 16339
Loading...
 
 ).
The GBM on-ground location, using the Fermi GBM trigger data,
is consistent with IPN triangulation.

The GBM light curve shows a complex structure, consisting of multiple peaks
with a total duration (T90) of about 13.6 s (50-300 keV).
The time-averaged spectrum from T0+1.024 s to T0+14.591 s is well fit
by a power law function with an exponential high-energy cutoff.
The power law index is -0.56 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 270 +/- 6 keV.


The event fluence (10-1000 keV) in this time interval is
(2.3 +/- 0.3)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+11.20 s in the 10-1000 keV band is 13.6 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."